ABSTRACT
The central nervous system disorders of adult life considered here fall into two main groups: the neurodegenerative disorders and dementias, and another group, of the psychiatric disorders of adult life, that has intriguingly close aetiological links with neurodevelopmental disorders although these links remain ill defined. Huntington's disease, due to an expanded and unstable trinucleotide repeat, represents one of the most difficult genetic counselling problems among the Mendelian disorders of adult life. Parkinsonian features may occur in more general brain degenerations, such as frontotemporal and Lewy body dementias, prion disease, spinocerebellar ataxias, Wilson disease and others, including non-genetic disorders and weakly genetic disorders. Alzheimer’s disease is the most common dementia of old age, and increased survival makes it a major problem for society as well as for individual families. Late-onset ataxia accompanied by upper motor neurone signs is a heterogenous group and has been found to result from trinucleotide repeat expansions in specific genes.
